In the field of optical fiber cables, optical fibers may typically be loosely bundled (loose tube arrangement) into multi-fiber tubes that are in turn coated with an outer jacket. Because the optical fibers are fragile and attenuation can occur with significant bending of the fibers, the tube and jacket arrangement is used to provide physical protection for the fibers to protect them against various environmental and mechanical stresses.
The manufacturing considerations have become more significant in view of recent attempts to make optical fibers that involve the bundling a plurality of fibers in a first tube and a plurality of fibers in a second tube, and applying a jacket over both tubes simultaneously, resulting in a multi-tube fiber optic cable having two haves, each jacketed independently, but connected via a central and breakable web (herein after collectively referred to as a multi-tube optical fiber cable). When making this product, it is difficult to calibrate the extrusion process so that the web separates without damaging the jacket covering the bundles (tube and yarn combination). Because the web needs to be strong enough to survive initial installation yet easily breakable by the user when desired, without damaging the jacket on either half of the cable, the calibration of the size of the web and extrusion thereof is difficult.
Various draw down and pressure extrusion techniques for the jacket simply move the strength yarns around the tube to one side or the other on both halves of the cable. The end result is that the yarns bunch up to one side periodically, causing the jacket to thin near the connection to the web. This frequently results in damage to the jacket when a user separates the two tubes, as the web is sometimes stronger than the near portion of the jacket to which it is connected. Furthermore, using a process of tube-on extrusion, while possibly allowing the web to form properly, does not provide significant adhesion between the jacket and the yarns.